The invention relates to keys which not only secure electrical connectors to circuit boards, but also insure that only the proper connectors can be used together.
It is often necessary or desirable to mount electrical connectors, such as header and shroud connectors on opposite sides of a printed circuit board, typically referred to as a mother board. Various keys are known in the prior art for accomplishing this mounting arrangement by clamping the circuit board between the header and shroud. Such keys however, have been generally unsatisfactory inasmuch as they are often relatively expensive, will not permit simultaneous keying to both the header and shroud, are difficult to use and/or are not substantial enough to securely attach the header and shroud to the circuit board. It is particularly necessary that such keys be relatively strong so that they do not become crushed or disabled if a wrong connector is used.
A further requirement of the key for some applications is that it be capable of being engaged by a single person working from on one side of the circuit board only. Keys which require simultaneous access to both sides render it more difficult to work with circuit boards. Also such keys of the prior art have a unique, typically polygonal, cross-section for "coding" the keys to the different types of connectors to ensure that only the proper connectors can be coupled. Unfortunately if these prior art keys are used, the coding features often cannot be used on dual sided connector applications unless the connector is left uncoupled to the circuit board. Their use has been limited from a practical standpoint to single sided applications.